Polysulfurized olefins

ABSTRACT

Sulfurized olefins are produced by (1) reacting sulfur monochloride with a stoichiometric excess of a low-carbon atom olefin, (2) treating the resulting product with an alkali metal sulfide in the presence of free sulfur in an alcohol-water solvent, and (3) reacting that product with an inorganic base. This reaction sequence produces novel stable oil-soluble organic sulfides having extreme pressure properties and low corrosiveness to metal. Lubricating oil compositions containing an effective amount of these additives evidence good load carrying capability.

United States Patent [15] 3,697,499 Myers [4 Oct. 10, 1972 [54]POLYSULFURIZED OLEFINS 2,708,199 [1955 Eby ..260/139 X [72] Inventor:Herbert Myers, Barrington, NJ. Primary Exa he J08 hRebold eP [73]Assrgnee: Mobil 0|] Corporation Assistant Examiner-D. R. Phillips 22 PH(1: M 15 1969 Attorney-Oswald G. Hayes, Raymond W. Barclay, 1 e AndrewL. Gabariault and Claude E. Setleff [21] Appl. No.: 842,055

Related US. Application Data [57] ABS CT Sulfurized olefins are producedby (1) reacting sulfur [62] 3 ggsfz j March 1967 monochloride with astoichiometric excess of a lowa carbon atom olefin, (2) treating theresulting product with an alkali metal sulfide in the presence of freesul- "260/139 252/ fur in an alcohol-water solvent, and (3) reactingthat [58] Feid (SO/:25 139 product with an inorganic base" This reaction1 0 re sequence produces novel stable oil-soluble organic sulfideshaving extreme pressure properties and low [56] References Citedcorrosiveness to metal. Lubricating oil compositions UNITED STATESPATENTS containing an effective amount of these additives 2 249 312 9 1K m al 260/ evidence good load carrying capability. 2,467,713 1949Watkins ..252/139 X 10 Claims, No Drawings POLYSULFURIZED OLEFINSCROSS-REFERENCE TO RELATED INVENTIONS This application is a division ofcopending application Ser. No. 620,621 filed Mar. 6, 1967, now US. Pat.No. 3,471,404.

FIELD OF THE INVENTION This invention relates to sulfurized olefins andin particular to polysulfurized olefins used in lubricating oilcompositions and to a method for preparing the same.

DESCRIPTION OF PRIOR ART Organic sulfur compounds have been known asadditives for lubricating oils. These compounds provide extreme pressureproperties to lubricants especially under high speed shock conditions.Unfortunately, the

1 presence of sulfur in lubricating oils causes considerable corrosionof metals, particularly copper. Since lubricating oils often operate atrelatively high temperatures, thermally unstable sulfur compounds maybreak down resulting in loss of the extreme pressure property and inincreased metal corrosion. In U. S. Pat. No. 2,708,199, there isdisclosed a method of producing organic polysulfides from olefins havingfrom six to 30 carbon atoms resulting in polymers of the olefincontaining two to three sulfur atoms per unsaturated bond of the olefin.However, without proper control of the reaction conditions, theresulting compound may be highly corrosive and unstable. Moreover, ifolefins of less than six carbon atoms were used in this process, oilinsoluble products would be obtained.

SUMMARY OF THE INVENTION It has now been unexpectedly discovered thatnovel stable non-corrosive organosulfur compounds which aresubstantially monomeric may be prepared by the steps of l) reacting asulfur chloride with an excess of an olefin, (2) reacting the resultingadduct with an alkali metal sulfide and free sulfur in a mole ratio ofno less than 2:1 and (3) treating the product of step (2) with aninorganic base.

DESCRIPTION OF SPECIFIC EMBODIMENTS The olefin reactant used in thisinvention may contain from about two to about five carbon atoms. Thepreferred number of the carbon atoms of the olefin ranges from three toabout five. Such olefins as butylene, isobutylene or amylene andisoamylene may be used; in particular, the branched-chain olefins arethe most preferred in accordance with this invention. It has been hereindiscovered that isobutylene has unexpectedly greater reactivity tosulfur chloride than other olefins and yields highly stable reactionproducts.

In the first step, sulfur monochloride is reacted with from 1 to 2moles, and preferably from 1.25 to L8 moles, of the olefin per mole ofthe sulfur monochloride. The reaction is carried out by mixing the tworeactants at a temperature from 20 C. to about 80 C. and preferably 30to 50 C. The olefin is introduced into the liquid sulfur monochloridesubsurface, at a rate commensurate with the absorption rate of theolefin into the sulfur monochloride. This reaction may take from aperiod of from 1 to 10 hours, although it is preferred that the reactiontime be carried out as rapidly as possible.

The second step in the process of this invention requires reacting theadduct of the first step with an valkali metal sulfide and free sulfur.In this reaction, the adduct is combined with a mixture of the alkalimetal sulfide, preferably sodium sulfide, and sulfur. The mixtureconsists of up to about 2.2 moles of the metal sulfide per gram-atom ofsulfur and preferably the ratio is L8 to 2.2. The mole ratio of alkalimetal' sulfide to adduct is about 0.8 to about 1.2 moles of metalsulfide per mole of adduct. These ratios are both considered significantin the practice of this invention. They have been found to contribute tothe oil solubility and thermal stability of the final product. Thisreaction, furthermore, is carried out in the presence of an alcohol oran alcohol-water solvent under reflux conditions. The alcohol may bepresent in a concentration in the water of from 5 percent to 25 percentby weight. Water-soluble alcohols, such as methanol, ethanol, propanol,isopropanol, butanol, and the like, may be used. The reflux time rangesfrom 3 to 6 hours.

The third step in the process of this invention is the reaction betweenthe polysulfurized olefin, which contains from about 1 to about 3percent of chlorine, with an inorganic base in a water solution. Alkalimetal hydroxide may be used, particularly sodium hydroxide, at aconcentration of about 5 to about 20 percent and preferably about 8 to12 percent, by weight in water. The reaction must be continued until thechlorine content is below 0.5 percent. The concentration of the alkalimetal hydroxide in water also appears to be of an important nature inthe preparation of the desirable product, and therefore the preferredrange represents an effective concentration level. Higher concentrationsmay degrade the product severely and lead to reaction products whichcould not be separated from the reaction mass easily. The alkali metalhydroxide treatment of the polysulfurized olefin is performed underreflux conditions for from 1 to 24 hours, although no more than 8 hoursare usually sufficient. Other inorganic bases which may be used includealkali metal carbonates and ammonia. However, the alkali metalhydroxides, and particularly sodium hydroxide, produce the mostdesirable product as evidenced by the low degree of corrosiveness tocopper metal.

The exact structure of the product is not known. It may consist ofmonomers containing sulfur or monomers bridged in a cyclic structure bythe sulfur. It believed that about percent or more of the product ismade up of monomeric sulfides and the cyclic derivatives thereof. Animportant feature of these oil-soluble polysulfurized olefins is thatthe products of this invention contain from about 40 to about 60percent, preferably 46 to 50 percent, sulfur in stabilized form, andless than 0.5 percent chlorine. Although the broadly described processmay yield products having utility in lubricating compositions, theproducts produced by adhering to the express limitations of the processof this invention are unexpectedly thermally stable and relativelynon-corrosive in lubricant compositions used in the presence of coppermetal and other sulfur-corrodible metals.

The organic sulfide produced by the method of this invention are oilsoluble, extreme pressure additives for lubricating oils, transmissionfluids or greases which occasion little or no corrosion to copper. Theadditive can be used in the conventional lubricating base media,

such as naphthenic and paraffinic mineral oils and synthetic lubricants,such as hydrocarbon fluids, glycol ether fluids', polysiloxane fluids,acetals, polyphenyl ethers, and the synthetic ester lubricants producedfrom monohydric alcohols and polycarboxylic acids and polyhydricalcohols, such as trimethylolpropane and pentaerythritol, and carboxylicacids having from to about 20 carbon atoms.

The followingexamples presented as an illustration of this invention andare not considered limiting any aspect thereof.

PREPARATION OF PRODUCT Into a 5-liter reaction flask was added 2,025grams (15.0 moles of sulfur monochloride) and the contents were heatedto 45 C. Through a sub-surface gas sparger, 1,468 grams (26.2 moles ofisobutylene gas) was fed into the reactor over a 5-hour period. Thetemperature was maintained between 45 and 50 C. At the end of thesparging, the reaction flask had an increase,

in weight of 1,352 grams.

Into a l2-liter reaction flask were added 2,150 grams (16.5 moles) of 60percent flake sodium sulfide, 240 grams (7.5 moles) sulfur, and asolution of 420 ml of isopropanol in 4,000 ml. of water. The contentswere heated to 40 C. The adduct of the sulfur monochloride andisobutylene previously prepared was added over a 52-hour period whilepermitting the temperature to rise to 75 C. The reaction mixture wasrefluxed for 6 hours, and afterward the mixture was permitted to forminto separate layers. The lower aqueous layer was discarded. The upperorganic layer was mixed with 2 liters of 10 percent aqueous sodiumhydroxide and the mixture was refluxed for 6 hours. The organic layerwas again. removed and washed with 1 liter of water. The washed productwas dried by heating at 90 C. and 30 mm Hg pressure .for 30 minutes. Theresidue was filtered through diatomaceous earth filter aid to give 2,070grams of a clear yellow-orange liquid.

The. analysis of this product was as follows:

% Sulfur 46.4 Chlorine 0.2

EVALUATION OF PRODUCT 1. Load Carrying Test The product of Example 1 wasevaluated in the SAE LoadCarr'ying Test as a lubricating oil additive.In this a gear lubricant is measured under high speed shock conditions.The oil composition, using a SAE-90 solvent refined Mid-Continent oil asthe base oil, is placed in the SAE test machine as a lubricant for twosteel test rings. These rings are rotated to produce a combination ofrolling and sliding actions while a gradually increasing load ismechanically applied. The tests were conducted at 500 rpm. The resultsare reported as lbs. (scale reading) at the point atwhich scoring orseizure occurs signifying the failure of the lubricant. The maximumreading on the scale is 460 lbs.

The results are tabulated below 2. Corrosion and Stability Tests The oilsample, tested in the previous test, was subjected to two hightemperature tests. In one test, the sample is heated to 250 F. and heldat that temperature for 3 hours, in the presence of copper metal. At theend of a 3-hour period, the surface of the copper is observed forcorrosion. In the second test, the sample lubricant is splashed onto atared aluminum panel heated to 500 F. A mechanical splasher throws theoil against the panel. The operation is conducted for 6 hours afterwhich time the panel is cooled down and weighed. This test, a well-knownhigh temperature oxidation test. of oil compositions, is used todetermine the tendencies of such compositions to form solid depositswhen in contact with high temperature surfaces. The results of the twotests are as follows:

Test Result 2A" 1 mg wt. gain Copper Corrosion Panel Coking Thesulfurized olefins of this invention are found to be useful additivesfor lubricating oils. They provide load carrying properties andanti-oxidant properties. Moreover, they are stable at high temperaturesand cause little or no corrosion to copper. In addition, they arecompatible with the other additives normally used in lubricatingcompositions, such as anti-oxidants, extreme pressure agents, viscositycontrol agents, detergents and the like.

The description and disclosure of the preferred embodiments of thisinvention are not to be construed as presenting limitations of theinvention. except as defined and limited in the following claim.

I claim:

1. A polysulfurized olefin produced by the stepsof (1) reacting sulfurmonochloride with from 1 to 2 moles of isobutylene per mole of saidsulfur monochloride at a temperature of from 20 C to about C, (2)reacting this product with an alkali metal monosulfide and free sulfur,wherein the ratio of the moles of alkali metal monosulfide to thegram-atoms of free sulfur is from about 1.8 to about 2.221, and (3)reacting this product with an aqueous solution containing from about 5to about 20 percent of an alkali metal hydroxide for a time sufficientto reduce the chlorine content below about 0.5 percent.

2. The polysulfurized isobutylene of claim 1 wherein the mole ratio ofolefin to sulfur monochloride is from about 1 to 2:1.

3. The polysulfurized olefin of claim 2 wherein the mole ratio ofisobutylene to sulfur monochloride is from about 1.25 to 1.821.

4. The polysulfurized olefin of claim 1 wherein the polysulfurizedolefin contains from about 40 to abo"t 60 percent of sulfur.

5. The polysulfurized olefin of claim 4 wherein the polysulfurizedolefin contains from about 46 to about 50 percent of sulfur.

6. The polysulfurized olefin of claim 1 wherein the polysulfurizedolefin is produced by reacting sulfur 9. The polysulfurized olefin ofclaim 1 wherein the mole ratio of alkali metal monosulfide to sulfurmonochloride-olefin product is from about 0.8 to about 1:2.

10. The polysulfurized olefin of claim 1 wherein the alkali metalmonosulfide and sulfur are reacted with the sulfur monochloride-olefinproduct in the presence of a water-soluble alcohol.

" Po-ioso UNITED STATESIPATENT OFFICE.

6 CERTIFICATE OF CORRECTION Patent No. 3,697,499 Dated October 972Inventor) Herbert Meyers I It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

? In column 2, line 48 "It believed" should" be It is I believed Incolumn Claim 1, line 5 and 55 "The polysulfurized isobutylene of claim 1wherein mole ratio of olefin should be The polysulfurized olefin ofclaim 1 wherein the mole ratio of isobutylene Signed and sealed this20th day of February 1973.

SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

2. The polysulfurized isobutylene of claim 1 wherein the mole ratio ofolefin to sulfur monochloride is from about 1 to 2:1.
 3. Thepolysulfurized olefin of claim 2 wherein the mole ratio of isobutyleneto sulfur monochloride is from about 1.25 to 1.8:
 4. The polysulfurizedolefin of claim 1 wherein the polysulfurized olefin contains from about40 to about 60 percent of sulfur.
 5. The polysulfurized olefin of claim4 wherein the polysulfurized olefin contains from about 46 to about 50percent of sulfur.
 6. The polysulfurized olefin of claim 1 wherein thepolysulfurized olefin is produced by reacting sulfur monochloride withfrom 1.25 to 1.8 moles per mole of sulfur monochloride of isobutylene,reacting the product of that reaction with an alkali metal monosulfide,and 0.5 gram atoms of free sulfur per mole of metal monosulfide.
 7. Thepolysulfurized olefin of claim 1 wherein the alkali metal hydroxide issodium hydroxide.
 8. The polysulfurized olefin of claim 1 wherein thealkali metal monosulfide is sodium sulfide.
 9. The polysulfurized olefinof claim 1 wherein the mole ratio of alkali metal monosulfide to sulfurmonochloride-olefin product is from about 0.8 to about 1:2.
 10. Thepolysulfurized olefin of claim 1 wherein the alkali metal monosulfideand sulfur are reacted with the sulfur monochloride-olefin product inthe presence of a water-soluble alcohol.